Impingement/convection/microwave oven and method

ABSTRACT

A combination oven that is operable with convection air, impingement air and microwave energy in various combinations thereof. The oven has an oven chamber and a fan box that are located front to back. A fan in the fan box circulates heated air by discharging via openings in a top and a bottom and taking in via an intermediate opening of a baffle plate. Impingement plates are easily installed and removed in the oven chamber to provide impingement air upwardly or downwardly. At least one of the impingement plates is installed and removed by a sliding motion. Microwave energy is provided through the side walls of the oven chamber. Intake ports for cooling air are located in a bevel between the side walls and bottom wall of the oven&#39;s outer enclosure so as to allow the oven to be located right next to other structures, such as a wall. An interlock assembly is also provided for the oven door.

CROSS-REFERENCED APPLICATIONS

This application is a divisional application of U.S. patent application,Ser. No. 11/302,638, filed on Dec. 14, 2005, which claims the benefit ofU.S. Provisional Patent Application, Ser. No. 60/635,857, filed on Dec.14, 2004, U.S. Provisional Patent Application, Ser. No. 60/682,594,filed on May 19, 2005, and U.S. Provisional Patent Application, Ser. No.60/735,241, filed on Nov. 9, 2005, the entire contents of each arehereby incorporated by reference.

FIELD OF THE INVENTION

This invention relates to new and improved cooking ovens, systems, ovencontrollers and methods concerning microwave, convection and impingementcooking separately and in various combinations as well as cooling andinterlock features for cooking ovens in general.

BACKGROUND OF THE INVENTION

A cooking oven that has both convection and impingement modes is shownin U.S. Pat. No. 5,345,923 as a countertop oven with one or moreremovable air impingement supply structures. Each air impingement supplystructure includes a specially designed food rack disposed between upperand lower corrugated impingement air forming walls. The air impingementsupply structures are removably inserted into the oven's air impingementsupply structure cooking chamber for operation in the impingement mode.One or more of the air impingement supply structures can be removed andreplaced by a standard food rack for operation in a convection mode. Thecountertop oven requires n specially designed food racks for n airimpingement supply structures and up to n standard food racks. Thecountertop oven also uses a fan disposed adjacent a side wall of theoven chamber, which increases the side-to-side footprint of the oven.

A cooking oven that has both a microwave mode and an impingement mode isshown in U.S. Pat. No. 5,254,823 as an oven that has a rather largepreheated thermal reservoir (at least 60 pounds) so as to facilitaterapid heat transfer to ambient air in a plenum. However, such an oven isquite heavy and cumbersome for many applications. Moreover, the preheattime is considerable (up to two or more hours) and cooling of the oven'sexterior surfaces can be difficult and energy inefficient. The oven usesimpingement air from a top of the oven's cooking chamber. This willbrown or crisp the top of a food product but not the sides or bottombecause the browning effect of the impingement jets is lost when theimpingement jets merge to form a blanket or are reflected from ovenchamber surfaces. The oven has a single microwave energy feed into thebottom of the cooking chamber. This results in uneven microwave cookingas the bottom of the food product is exposed to direct microwave energyand the top of the food is exposed to indirect microwave energy.Moreover, if metal pans are used, bottom feed microwave energy resultsin a large amount of reflected microwave energy to the bottom feedaperture, which can considerably reduce the useful life of themagnetrons.

There is a need for an oven that can cook food with microwave energy,impingement air and/or convection air.

There is a need for a microwave oven that can use metal pans withimproved useful life of the magnetrons.

There is a further need for a light weight oven that has a smallfootprint.

SUMMARY OF THE INVENTION

A combination oven of the present invention comprises an oven chamberand at least one impingement air generator disposed in the oven chamberto provide impingement air that flows substantially in a verticaldirection within the oven chamber. A microwave generator is disposed toprovide microwave energy into the oven chamber via at least one wall ofthe oven chamber. A controller operates the oven in a microwave mode, animpingement mode or a combination microwave and impingement mode.

In one embodiment of the oven of the present invention, the wall isvertical.

In another embodiment of the oven of the present invention, the wall isa back wall or a side wall.

In another embodiment of the oven of the present invention, themicrowave generator provides the microwave energy via two walls of theoven chamber.

In another embodiment of the oven of the present invention, theimpingement air generator comprises a removable plate, a blower and anair heater.

In another embodiment of the oven of the present invention, the wall isa side wall and the oven further comprises a fan disposed in a fan boxto circulate heated air between the fan box and the oven chamber via abaffle plate. The impingement air generator comprises a plate thatconverts a portion of the circulating air to the impingement air.

In another embodiment of the oven of the present invention, the plate isremovable to convert the oven for operation in either a convection modeor a combination microwave and convection mode.

In another embodiment of the oven of the present invention, the plate isdisposed near a bottom wall of the oven chamber so that the impingementair flows upwardly.

In another embodiment of the oven of the present invention, the plate isdisposed near a top wall of the oven chamber so that the impingement airflows downwardly.

In another embodiment of the oven of the present invention, anadditional plate is disposed near a top wall of the oven chamber so thatanother portion of the impingement air flows downwardly.

In another embodiment of the oven of the present invention, the platehas a handle to facilitate installation and removal by a sliding motion.

In another embodiment of the oven of the present invention, the platecomprises a front and opposed sides separated by a wall that contains anarray of jet holes shaped to provide the impingement air.

In another embodiment of the oven of the present invention, the plate isinstallable in and removable from the oven chamber.

In another embodiment of the oven of the present invention, the plate isinstalled substantially flush with the baffle plate to receivecirculating air from the fan box. The plate comprises a diverter toprovide a substantially uniform pressure to the jet holes, whetherlocated near or remote from the baffle plate.

In another embodiment of the oven of the present invention, themicrowave generator also provides microwave energy into the oven chambervia an opposite side wall of the oven chamber. The microwave generatorcomprises one or more magnetrons and one or more wave guides to providethe microwave energy.

In another embodiment of the oven of the present invention, the ovencomprises an outer enclosure comprising at least a first side wall andan additional wall that is substantially perpendicular to the first sidewall and connected to the first side wall by a portion that is inwardlyoffset from the first side wall. An inner enclosure is disposed withinand spaced from the outer enclosure by a passageway. A cooling fan isdisposed within the passageway and is operable to maintain a flow ofcooling air in the passageway between at least one intake port and oneor more output ports. The intake port is located in the offset portionof the outer enclosure.

In another embodiment of the oven of the present invention, the outerenclosure further comprises a second side wall. The additional wall isinwardly offset from the second side wall by an additional offsetportion. An additional intake port is located in the additional offsetportion.

In another embodiment of the oven of the present invention, the offsetportion comprises a first bevel between the additional wall and thefirst side wall, and wherein the additional offset portion comprises asecond bevel between the additional wall and the second side wall.

In another embodiment of the oven of the present invention, theadditional wall is a bottom wall.

In another embodiment of the oven of the present invention, the outputport is located in a back wall of the outer enclosure.

In another embodiment of the oven of the present invention, an airfilter disposed at the intake port.

In another embodiment of the oven of the present invention, a first airfilter is disposed in the intake port and a second air filter isdisposed at the second intake port.

In another embodiment of the oven of the present invention, a first airfilter holder and a second air filter holder that enables easyinstallation and removal of the first air filter and the second airfilter, respectively, are provided.

In another embodiment of the oven of the present invention, the firstair filter holder and the second air filter holder are configured forinstallation and removal by a sliding motion of the respective airfilters.

In another embodiment of the oven of the present invention, a source ofcooking energy is disposed to provide cook energy to the inner enclosureto cook food therein.

A method of the present invention operates an oven that includes an ovenchamber. The method comprises:

providing impingement air that flows substantially vertically in theoven chamber;

providing microwave energy into the oven chamber via at least one wallof the oven chamber; and

controlling the oven such that it operates in either a microwave mode,an impingement mode or a combination microwave and impingement mode.

In one embodiment of the method of the present invention, the wall isvertical.

In another embodiment of the method of the present invention, the wallis a back wall or a side wall.

In another embodiment of the method of the present invention, themicrowave energy is provided by a microwave generator via two walls ofthe oven chamber.

In another embodiment of the method of the present invention, a furtherstep comprises installing in and removing from the oven chamber aremovable impingement plate.

In another embodiment of the method of the present invention, theimpingement plate is installable in and removable from the oven chamberwith a sliding motion.

In another embodiment of the method of the present invention, the wallis a side wall and further steps comprise running a fan disposed in afan box to circulate heated air between the fan box and the oven chambervia a baffle plate, and converting a portion of the circulating air tothe impingement air.

In another embodiment of the method of the present invention, theconverting step uses at least one impingement plate disposed in the ovenchamber to convert the circulating air to impingement air.

In another embodiment of the method of the present invention, theimpingement plate is removable to convert the oven for operation in aconvection mode or a combination microwave and convection mode.

In another embodiment of the method of the present invention, theimpingement plate is disposed near a bottom wall of the oven chamber sothat the impingement air flows upwardly.

In another embodiment of the method of the present invention, theimpingement plate is disposed near a top wall of the oven chamber sothat the impingement air flows downwardly.

In another embodiment of the method of the present invention, anadditional impingement plate is disposed near a top wall of the ovenchamber so that another portion of the impingement air flows downwardly.

In another embodiment of the method of the present invention, furthersteps comprise installing and removing the impingement plate with asliding motion.

In another embodiment of the method of the present invention, theimpingement plate comprises a frame that includes a front and opposedsides separated by a wall that contains an array of jet holes shaped toprovide the impingement air.

In another embodiment of the method of the present invention, theimpingement plate further comprises a handle to facilitate installationand removal by a sliding motion.

In another embodiment of the method of the present invention, theimpingement plate is installed substantially flush with the baffle plateto receive circulating air from the fan box, and wherein the impingementplate comprises a diverter to provide a substantially uniform pressureto the jet holes, whether located near or remote from the baffle plate.

In another embodiment of the method of the present invention, themicrowave energy is also provided into the oven chamber via an oppositeside wall of the oven chamber.

In another embodiment of the method of the present invention, themicrowave energy is also provided into the oven chamber via an oppositeside wall of the oven chamber.

Another method of the present invention comprises the steps of:

providing an outer enclosure comprising at least a first side wall andan additional wall that is substantially perpendicular to the first sidewall and connected to the first side wall by a portion that is inwardlyoffset from the first side wall;

providing an inner enclosure disposed within and spaced from the outerenclosure by a passageway;

running a cooling fan that is disposed within the passageway to maintaina flow of cooling air in the passageway between at least one intake portand one or more output ports; and

providing the intake port in the offset portion of the outer enclosure.

In another embodiment of the method of the present invention, the outerenclosure further comprises a second side wall. The additional wall isinwardly offset from the second side wall by an additional offsetportion. An additional intake port is located in the additional offsetportion.

In another embodiment of the method of the present invention, the offsetportion comprises a first bevel between the additional wall and thefirst side wall. The additional offset portion comprises a second bevelbetween the additional wall and the second side wall.

In another embodiment of the method of the present invention, theadditional wall is a bottom wall.

In another embodiment of the method of the present invention, the outputport is located in a back wall of the outer enclosure.

In another embodiment of the method of the present invention, an airfilter is disposed at the intake port.

In another embodiment of the method of the present invention, a firstair filter is disposed at the intake port and a second air filter isdisposed at the second intake port.

In another embodiment of the method of the present invention, a firstair filter holder and a second air filter holder that enables easyinstallation and removal of the first air filter and the second airfilter, respectively, are provided.

In another embodiment of the method of the present invention, the firstair filter holder and the second air filter holder are configured forinstallation and removal by a sliding motion of the respective airfilters.

In another embodiment of the method of the present invention, cookenergy is provided to the inner enclosure to cook food therein.

Another oven of the present invention comprises a frame, a door and ahinge that is connected with the door and the frame for rotating thedoor about a pivot as the door is opened and closed. A cam moves as thedoor rotates. An interlock assembly comprises first and second switchesand responds to the motion of the cam to activate the first and secondswitches in sequence as the door opens and closes.

In another embodiment of the oven of the present invention, the firstand second switches are micro-switches.

In another embodiment of the oven of the present invention, theinterlock assembly further comprises a plunger that is mounted forreciprocal motion and that activates the first and second micro-switchesin response to the cam motion.

In another embodiment of the oven of the present invention, the plungeris shaped to control the sequence.

In another embodiment of the oven of the present invention, the firstand second micro-switches comprise a first contact element and a secondcontact element, respectively, that are engaged by and tripped by thereciprocal motion of the plunger.

In another embodiment of the oven of the present invention, the plungeris shaped with first and second contours that are disposed in engagementwith the first and second contact elements of the first and secondmicro-switches, respectively, wherein the first and second contours areshaped to activate the first and second micro-switches in sequence asthe plunger is moved.

In another embodiment of the oven of the present invention, theinterlock assembly further comprises a spring that compresses as thedoor closes and decompresses as the door opens to return the plunger toa door open position.

A system of the present invention comprises an oven chamber and an ovenrack disposed in the oven chamber to hold a metal pan that contains thefood product. A microwave generator provides microwave energy into theoven chamber via at least one vertical wall of the oven chamber torapidly cook the food product. An impingement air generator thatprovides impingement air substantially in a vertical direction in theoven chamber to brown the food product.

In another embodiment of the system of the present invention, themicrowave generator includes a microwave source that provides themicrowave energy into the oven via a feed aperture in the vertical wall,and wherein the food rack is located below the feed aperture so as tominimize microwave energy incident to the feed aperture that isreflected by the metal pan, thereby prolonging the longevity of themicrowave source.

In another embodiment of the system of the present invention, thevertical wall is a side wall of the oven chamber.

In another embodiment of the system of the present invention, themicrowave generator also provides the microwave energy into the ovenchamber via an opposite side wall.

In another embodiment of the system of the present invention, theimpingement air generator comprises a plate that is manually installableand removable so as to convert the system back and forth between acombination of impingement and microwave and a combination of convectionand microwave.

In another embodiment of the system of the present invention, acontroller and a cooling fan that cools the microwave generator areprovided. The controller regulates a speed of the cooling fan based on atemperature sensed by a probe in a vicinity of the microwave facility toreduce the speed as the sensed temperature falls and to increase thespeed as the sensed temperature rises.

A controller of the present invention controls an oven that comprises atleast one microwave generator. The controller comprises a processor anda memory containing a control program. The control program comprises oneor more instructions that cause the processor to perform the steps of:

-   -   sampling an output of a temperature sensor located in the        vicinity of the microwave generator for a current temperature of        the microwave generator;    -   determining whether the current temperature is acceptable; and    -   if the current temperature is unacceptable, causing the oven to        be disabled.

In another embodiment of the controller of the present invention, themicrowave generator comprises at least one magnetron.

In another embodiment of the controller of the present invention, theoven is disabled automatically or manually by an operator as instructedby an error message notification generated by the processor.

In another embodiment of the controller of the present invention, thecurrent temperature is unacceptable if it is greater than apredetermined overheat temperature.

In another embodiment of the controller of the present invention, thecurrent temperature is also unacceptable if it is less than apredetermined cold temperature.

In another embodiment of the controller of the present invention, thecurrent temperature is unacceptable when the current temperature fails acomparison test with a reference value a predetermined number of times.

Another controller of the present invention controls an oven thatcomprises at least one microwave generator. The controller comprises aprocessor and a memory containing a control program. The control programcomprises one or more instructions that cause the processor to run themicrowave generator for N cooking stages and a remainder cooking stageat a predetermined duty cycle, where N is the total cooking time for afood product divided by a predetermined cooking stage period and theremainder is a remainder of the division.

In another embodiment of the controller of the present invention, theinstructions cause the processor to perform the further steps of:

-   -   calculating N and the remainder; and    -   calculating the on and off time of the microwave generator for        the N cooking stages and the remainder cooking stage, based on        the predetermined duty cycle.

Another controller of the present invention controls an oven thatcomprises an oven chamber. The controller comprises a processor and amemory containing a control program. The control program comprises oneor more instructions that cause the processor to control the oven for acool down mode with steps comprising:

sampling an output of a temperature sensor located in the oven chamberfor a current oven temperature;

determining if the current temperature is too hot;

if the current temperature is too hot, notifying an operator to placeice in the oven chamber;

repeating the sampling and determining steps until the oven chamber isdetermined to be cool; and

notifying the user that the oven chamber is cool.

In another embodiment of the controller of the present invention, theinstructions cause the processor to perform a further step of adjustinga speed of a cooling fan of the oven to a higher speed to assist in thecool down mode.

Another controller of the present invention controls an oven thatcomprises a cooling fan. The controller comprises a processor and amemory containing a control program. The control program comprises oneor more instructions that cause the processor to control the cooling fanwith steps comprising:

sampling an output of a temperature sensor for a current temperature;and

adjusting a speed of the cooling fan based on the current temperature.

In another embodiment of the controller of the present invention, alocation of the temperature sensor is selected from the group consistingof: ambient, oven chamber and temperature sensitive components.

Another controller of the present invention controls an oven. Thecontroller comprises a processor and a memory containing a controlprogram. The control program comprises one or more instructions thatcause the processor to control an oven profile with steps comprising:

displaying to an operator a plurality of profile entry parameters;

modifying the profile entry parameters based on one or more inputsprovided by the operator; and

using the modified profile entry parameters to control the operation ofthe oven.

In another embodiment of the controller of the present invention, theprofile entry parameters are selected from the group consisting of:language, alarm volume, alarm sound, manual mode, automatic mode andtemperature units.

In another embodiment of the controller of the present invention, theprofile entry parameters are sequentially displayed to the operator.

Another controller of the present invention controls an oven. Thecontroller comprises a processor and a memory containing a controlprogram. The control program comprises one or more instructions thatcause the processor to control a transfer of data with a data carryingkey with steps comprising:

detecting an input from a key reader that reads the key;

identifying from data carried by the key an operation of upgradefirmware, program download or program upload; and

executing the identified operation.

In another embodiment of the controller of the present invention, thecontroller performs the further steps of:

transferring the data of the identified operation;

doing a checksum of the transferred data;

validating the transferred data; and

notifying an operator that the operation is completed.

A method of the present invention uses a computer to control an oventhat has at least one microwave generator. The method comprises:

sampling an output of a temperature sensor located in the vicinity ofthe microwave generator for a current temperature of the microwavegenerator;

determining whether the current temperature is acceptable; and

if the current temperature is unacceptable, causing the oven to bedisabled.

In another embodiment of the method of the present invention, themicrowave generator comprises at least one magnetron.

In another embodiment of the method of the present invention, the ovenis disabled automatically or manually by an operator as instructed by anerror message notification generated by the processor.

In another embodiment of the method of the present invention, thecurrent temperature is unacceptable if it is greater than apredetermined overheat temperature.

In another embodiment of the method of the present invention, thecurrent temperature is also unacceptable if it is less than apredetermined cold temperature.

In another embodiment of the method of the present invention, thecurrent temperature is unacceptable when the current temperature fails acomparison test with a reference value a predetermined number of times.

Another method of the present invention uses a computer to control anoven that comprises at least one microwave generator. The methodcomprises:

running the microwave generator for N cooking stages and a remaindercooking stage at a predetermined duty cycle, where N is the totalcooking time for a food product divided by a predetermined cooking stageperiod and the remainder is a remainder of the division.

In another embodiment of the method of the present invention, the methodfurther comprises:

-   -   calculating N and the remainder; and    -   calculating the on and off time of the microwave generator for        the N cooking stages and the remainder cooking stage, based on        the predetermined duty cycle.

Another method of the present invention uses a computer to control anoven that comprises an oven chamber. The method comprises:

sampling an output of a temperature sensor located in the oven chamberfor a current oven temperature;

determining if the current temperature is too hot;

if the current temperature is too hot, notifying an operator to placeice in the oven chamber;

repeating the sampling and determining steps until the oven chamber isdetermined to be cool; and

notifying the user that the oven chamber is cool.

In another embodiment of the method of the present invention, the methodfurther comprises: adjusting a speed of a cooling fan of the oven to ahigher speed to assist in the cool down mode.

Another method of the present invention uses a computer to control anoven that comprises a cooling fan. The method comprises:

sampling an output of a temperature sensor for a current temperature;and

adjusting a speed of the cooling fan based on the current temperature.

In another embodiment of the method of the present invention, a locationof the temperature sensor is selected from the group consisting of:ambient, oven chamber and temperature sensitive components.

Another method of the present invention uses a computer to control anoven. The method comprises:

displaying to an operator a plurality of profile entry parameters;

modifying the profile entry parameters based on one or more inputsprovided by the operator; and

using the modified profile entry parameters to control the operation ofthe oven.

In another embodiment of the method of the present invention, theprofile entry parameters are selected from the group consisting of:language, alarm volume, alarm sound, manual mode, automatic mode andtemperature units.

In another embodiment of the method of the present invention, theprofile entry parameters are sequentially displayed to the operator.

Another method of the present invention uses a computer and a datacarrying key to control an oven. The method comprises:

detecting an input from a key reader that reads the key;

identifying from data carried by the key an operation of upgradefirmware, program download or program upload; and

executing the identified operation.

In another embodiment of the method of the present invention, the methodfurther comprises:

transferring the data of the identified operation;

doing a checksum of the transferred data;

validating the transferred data; and

notifying an operator that the operation is completed.

BRIEF DESCRIPTION OF THE DRAWINGS

Other and further objects, advantages and features of the presentinvention will be understood by reference to the following specificationin conjunction with the accompanying drawings, in which like referencecharacters denote like elements of structure and:

FIG. 1 is a perspective view of the oven of the present invention;

FIG. 2 is a rear view of the oven of FIG. 1;

FIG. 3 is a perspective view of an air filter frame for the oven of FIG.1;

FIG. 4 is a cross-sectional view along line 4 of FIG. 1 that depicts theoven in a convection mode;

FIG. 5 is a cross-sectional view along line 4 of FIG. 1 that depicts theoven in an impingement mode;

FIG. 6 is a view along line 4 of FIG. 1 that depicts the oven in amicrowave mode;

FIG. 7 is a perspective view of a portion of the oven of FIG. 1 with theoven door open that depicts the lower impingement plate installed;

FIG. 8 is a perspective view of a portion of the oven of FIG. 1 with theoven door open that depicts the upper impingement plate installed;

FIG. 9 is a top view of the lower impingement plate of the oven of FIG.1;

FIG. 10 is a cross-sectional view of FIG. 7 along line 10;

FIG. 11 is a perspective view of the upper impingement plate of the ovenof FIG. 1;

FIG. 12 is a front view of the upper impingement plate of the oven ofFIG. 1;

FIG. 13 is a detail view of an interlock assembly mounted in place on ahinge of the door of the oven of FIG. 1;

FIG. 14 is a perspective view of the interlock assembly of FIG. 13;

FIG. 15 is a top view of the interlock assembly of FIG. 14;

FIG. 16 is a front view of the interlock assembly of FIG. 14;

FIG. 17 is a side view of the interlock assembly of FIG. 13

FIG. 18 is a perspective view of another embodiment of the oven of thepresent invention;

FIG. 19 depicts a portion of the oven of FIG. 18 with the door open;

FIG. 20 is a view along line 20 of FIG. 21;

FIG. 21 is a cross-sectional view along line 21 of FIG. 18;

FIG. 22 is a block diagram of the controller of the oven of FIG. 1; and

FIGS. 23-28 are flow diagrams of program mode features of the controllerof FIG. 22.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIGS. 1 and 2, a combination oven 30 of the presentinvention comprises a pair of outer side walls 32 and 34, an outer backwall 36, an outer top wall 38, an outer bottom wall 40 and a front wall41, all of which comprise an outer enclosure. Front wall 41 comprises adoor 42, a control panel 44 above door 42 and a grease drawer 46 belowdoor 42. A handle 48 is disposed on door 42 for opening the door in apull down manner.

Outer bottom wall 40 is offset from outer side walls 32 and 34, outerback wall 36 and front wall 41. The offset is preferably a bevel 50, butcould be have other shapes. An air intake port 52 and an air intake port54 are located in opposed sides of bevel 50 adjacent outer side walls 32and 34, respectively. Air filters 56 and 58 are disposed at air intakeports 52 and 54, respectively. Ambient air is taken in via air intakeports 52 and 54 to cool various control parts, a fan motor (not shown),outer side walls 32 and 34, outer bottom wall 40 and outer top wall 38and outer back wall 36. The cooling air exits oven 30 via a plurality oflouvers 60 disposed in outer back wall 36.

Combination oven 30 is configurable for operation in a convection mode,an impingement mode, a microwave mode, a combination convection andmicrowave mode, a combination impingement and microwave mode and acombination microwave, impingement and convection mode.

Referring to FIG. 4, combination oven 30 is shown configured for aconvection mode. Combination oven 30 comprises an oven chamber 70 and afan box 72 supported by a support structure 68, which is mechanicallyconnected to outer bottom wall 40 and outer side walls 32 and 34. Ovenchamber 70 and fan box 72 share an inner top wall 76, an inner bottomwall 78 and inner side walls 80 and 82, inner side wall 82 being shownonly in FIGS. 6 and 7. Oven chamber 70 and fan box 72 also share avertically disposed baffle plate 74. Thus, oven chamber 70 comprisesdoor 42, baffle plate 74, inner top wall 76, inner bottom wall 78 andinner side walls 80 and 82. Fan box 72 comprises baffle plate 74, innertop wall 76, inner bottom wall 78, inner side walls 80 and 82 and aninner back wall 84. A fan 85 is disposed in fan box 72 and a heater 87is disposed downstream of fan 85. Fan 85 may be any fan suitable forcirculating heated air in an oven. Preferably, fan 85 is a three phasecage induction motor suitable for inverter drive, preferably L7FWDS-638manufactured by Hanning. Heater 87 may be any heater (gas or electric)suitable for heating circulating air in a convection and/or impingementair oven. Preferably, heater 87 is an electrical heater having one ormore heating elements disposed above and below the blades of fan 85.

Referring to FIGS. 4 and 7, baffle plate 74 comprises a plurality ofopenings to provide a path for air to circulate between oven chamber 70and fan box 72. An opening 86 (shown only in FIG. 7) is located abovethe bottom of baffle plate 74. A grease filter 88 is mounted to baffleplate 74 to cover opening 86, which is preferably at least partially inregistration with fan 85. An opening 90 is located at or near the top ofbaffle plate 74. One or more openings 92 are located near the bottom ofbaffle plate 74.

Grease filter 88 is advantageously located upstream airflow to thesuction side of fan 85 to filter grease and/or other particles from thecirculating air stream before reaching the blades of fan 85. Greasefilter 88 is also located in a readily accessible position for removaland cleaning.

The oven chamber inner walls 80 and 82 are shaped so that grease andother liquid flows downwardly toward grease drawer or pan 46. Sincegrease drawer 46 is readily removable, it is easy to clean.

A catalyst structure 96 is disposed in fan box 72 between fan 85 andbaffle plate 74. Catalyst structure 96 comprises a catalyst 98, acatalyst 100 and a catalyst 102. Catalyst 98 is disposed adjacent innertop wall 76 in at least partial registration with opening 90 of baffleplate 74. Catalyst 100 is disposed at least in partial registration withgrease filter 88 and fan 85. Catalyst 102 is disposed in registrationwith openings 92. A fan cover 104 has an opening 106 and is disposedbetween fan 85 and catalyst 100 so that opening 106 is in registrationwith fan 85 and catalyst 100.

Catalyst 100 may suitably be a sheet material with a plurality ofapertures. For example, catalyst 100 may be 12×12 0.041 inch diameteropen wire mesh available from Englehard. Catalysts 98 and 102 maysuitably be 0.0006 inches metal foil hemingbone pattern substrate withplatinum catalyst 105 cell per square inch available from Englehard.

Referring to FIGS. 4 and 6, an oven rack 108 is disposed in oven chamber70 on supports 110 mounted to inner side walls 80 and 82 so that ovenrack 108 is near the bottom of grease filter 88 and above openings 92.Oven rack 108 may be a standard food rack, i.e., available off-shelf. Amicrowave opening 112 is disposed in inner side wall 80 and a microwaveopening 116 is disposed in inner side wall 82. A cover 114 and a cover118 are disposed to cover openings 112 and 116, respectively. Covers 114and 118 are microwave transparent. For example, the covers may be asuitable ceramic or other microwave transparent material.

Outer walls 32, 34, 36, 38 and 40, which comprise an outer enclosure,inner walls 76, 78, 80, 82 and 84, which comprise an inner enclosure,and baffle plate 74 are preferably a metal, such as stainless steel.

Inner walls 76, 78, 80, 82 and 84 are separated from outer walls 32, 34,36, 38 and 40 by a passageway 120 for cooling air in combination oven30. A cooling fan 122 is disposed in passageway 120 below oven chamber70 and between outer bottom wall 40 and inner bottom wall 78. A fanmotor compartment 124 and one or more microwave generators 126 (e.g.,magnetrons) are disposed in passageway 120 between outer back wall 36and inner back wall 84. A fan motor (not shown) is disposed in fan motorcompartment 124 and is coupled to rotate fan 85. A suitable thermalinsulation (not shown) is disposed in passageway 120 about oven chamber70 and fan box 72.

Referring to FIGS. 1-3, there is shown an air filter holder 130 thatpermits easy installation and removal of air filter 56. To this end, airfilter holder 130 comprises flanges 132 and 134 that are shaped forinstallation and removal of air filter 56 by a sliding motion. Airfilter holder 130 also comprises an opening 136 that is in registrationwith air intake port 52. Air filter holder 130 is mounted to bevel 50 byany suitable fastener, such as screws. Alternatively, air filter holder130 can be formed in bevel 50 by stamping or other metal workingprocess. It will be apparent to those skilled in the art that a similarair filter holder 130 is provided for air filter 58. Air filters 56 and58 each comprise an array of perforations. For example, the perforationsmay simply be the mesh of a screen, such as screen 138, a portion ofwhich is shown for air filter 56.

Referring to FIGS. 1-5, cooling fan 122 is operable to circulate coolingair in passageway 120. The cooling air is drawn into passageway 120 fromambient via air intake ports 52 and 54 and flows through passageway 120and exits via louvers 60 in outer back wall 36 to cool various controlparts, the fan motor (not shown), microwave generators 126, outer sidewalls 32 and 34, outer bottom wall 40, outer top wall 38 and outer backwall 36. By locating air intake ports 52 and 54 in bevel 50, combinationoven 30 can be located side by side with other structures (e.g., awall), i.e., outer side walls 32 and 34 being flush against the otherstructures. This conserves space and allows combination oven 30 to havea smaller footprint than prior ovens.

For convection operation of combination oven 30, fan 85 circulates airdrawn from oven chamber 70 into fan box 72 via grease filter 88 andcatalyst 100. The air is heated by heater 87 and circulated to ovenchamber via catalyst 98 and catalyst 102. Grease filter 88 and catalyst100 function to remove contaminates (e.g., grease particles and othercontaminates) from the air prior to contact with fan 85. Catalysts 98and 102 function to further purify the air prior to circulation intooven chamber 70.

Referring to FIG. 5, combination oven 30 is also configurable in animpingement mode by installing removable lower and/or upper impingementplates 150 and 152, respectively. Referring also to FIGS. 7 and 9, lowerimpingement plate 150 comprises a frame 154 that has a top side 156, afront side 158, a left side 160 and a right side 162. Top side 156comprises an array of jet holes 164 shaped to provide jets or columns ofimpingement air. Frame 154 is dimensioned for installation by slidingmotion along inner bottom wall 78. To facilitate installation andremoval, a handle 158 is disposed on top side 156. Also, as shown inFIG. 9, one or more guides or locators 166 are provided to assure thatframe 154 is installed flush with baffle plate 74 to minimize airleakage. Guides 166 mate with similar guides in baffle plate 74. Guides166 and their mating guides may be any suitable guides that mate, e.g.,tab and slot, flange and flange, and other mating guides.

When installed, impingement plate 150 forms with inner bottom wail 78 animpingement plenum that is in fluid communication with fan box 72 viaopenings 92 in baffle plate 74. Thus, airflow from fan box 72 throughholes 92 pressurizes lower impingement plate 150 to provide jets orcolumns impingement of impingement air toward oven rack 108, asindicated by the vertical upwardly extending arrows in FIG. 5.

Referring to FIG. 9, perforations or jet holes 164 in a central area oftop side 156 of impingement plate 150 are shown as closely spaced. Thisdirects most of the impingement air to a central area of oven rack 108so as to impinge directly on the food product. There are fewer jet holes164 (less closely spaced jet holes) near the edges. This assures thatmost of the impingement air will be concentrated toward the center forfood products like pizza.

Referring to FIGS. 5, 8, 11 and 12, upper impingement plate 152comprises a comprises a frame 170 that has a bottom side 172, a frontside 174, a left side 176 and a right side 178. Bottom side 172comprises an array of jet holes 180 shaped to provide jets or columns ofimpingement air as indicated by the vertical downwardly extending arrowsin FIG. 5. Front side 174, left side 176 and right side 178 extend abovebottom side 172. Front side 174, left side 176 and right side 178 arefastened to bottom plate 172 by any suitable fastener, such as screws,weldment or other suitable fastener. Alternatively, frame 170 can beformed as an integral one-piece construction. Frame 170 is dimensionedfor installation in oven chamber 70 against inner top wall 76 and baffleplate 74 in registration with opening 90 and catalyst 98. Upperimpingement plate 152 is installed with fasteners, such as screws 182 toinner top wall 76.

Upper impingement plate 152 together with inner top wall 76 and innerside walls 80 and 82 of oven chamber 70 form a delivery plenum for theairflow through catalyst 98 to jet holes 180. As shown in FIGS. 11 and12, front side 174 is angled for an air diversion function to provide amore uniform air pressure throughout the delivery plenum to assure thatthe air jets 180 remote from the airflow entry at opening 90 have thesame velocity as those that are nearer to opening 90. If desired, thelower impingement plate could also be provided with an air diverter.

For impingement operation of combination oven 30, fan 85 circulates airdrawn from oven chamber 70 into fan box 72 via grease filter 88 andcatalyst 100. The air is heated by heater 87 and circulated to ovenchamber via catalysts 98 and 102 and lower and upper impingement plates150 and 152, respectively. As in the convection mode, grease filter 88and catalyst 100 function to remove contaminates (e.g., grease particlesand other contaminates) from the air prior to contact with fan 85.Catalysts 98 and 102 function to further purify the air prior tocirculation into lower and upper impingement plates 150 and 152 fordelivery as impingement air to oven chamber 70.

Combination oven 30 can also be operated in microwave and bothimpingement and convection mode by removal of either upper impingementplate 152 or lower impingement plate 150, but not both. If bothimpingement plates 150 and 152 are removed, oven 3 will function in aconvection mode or a combination convection and microwave mode.

Referring to FIG. 6, combination oven 30 is configured in a combinationmicrowave and impingement mode. Upper and lower impingement plates 150and 152 are installed. A microwave generator comprising one or moremagnetrons 126 (FIG. 4) and a pair of wave-guides (not shown) providesmicrowave energy through entry openings or ports 112 and 116 disposed ininner side walls 80 and 82, respectively. The wave-guides extend frommicrowave generators 126 in passageway 120 (FIGS. 4 and 5) to openings112 and 116. This combination of microwave energy feed from opposedinner side walls 80 and 82 and impingement air from above and/or belowis a significant feature of the present invention. Microwave energy fromboth inner side walls 80 and 82 provide direct microwave energy to thesides, top and bottom of a food product disposed on food rack 108.Impingement air from above and below impinges and browns the top andbottom of the food product. If browning is not desired on the bottom,for example, lower impingement plate 150 is removed. The oven then isconfigured for microwave, impingement (from the top) and convection. Analternative arrangement would be the removal of upper impingement plate152 while retaining lower impingement plate 150 for products thatrequire bottom browning and a gentle convection heat, i.e., delicatepastries. Due to microwave energy being launched from one or more sidewalls, metal pans can be used in oven 30. By locating oven rack 108below microwave feed ports 112 and 116, low profile metal pans, such asthose used for baking pastries and other foods, can be used to hold foodproducts during cooking without reflected microwave energy seriouslyimpairing the useful life of magnetrons 126.

Microwave energy is signified in FIG. 6 with arrows directed into ovenchamber 70 from openings 112 and 116. Impingement cooking is signifiedby the arrows in FIG. 4.

Cooling fan 122 is preferably a variable speed fan so as to minimizenoise and energy consumption while still maintaining low temperature ofcritical components. This is to be contrasted with known ovens that havea fixed speed cooling fan that is always on or a delayed turn-on and adelayed turn-off. Combination oven 30 comprises a temperature probe (notshown) that is located (e.g., in the vicinity of magnetrons 126) toprovide a signal proportional to temperature of critical or temperaturesensitive components. An oven controller (not shown) uses the signal toregulate the cooling fan speed accordingly. As an example, a magnetronwill only generate heat while it is operating, thereby requiring arelatively large amount of cooling air to keep the temperature sensitivecomponents from overheating. When the magnetron is turned off, only asmall amount of cooling air is needed to maintain certain areas under amaximum temperature. Regulating the cooling fan speed based on a measureof the temperature of the temperature sensitive components, not onlysaves energy spent by the cooling fan, but also minimizes heat loss fromthe oven cavity insulation. This feature also allows the controller toalert an operator for over heating conditions due to high temperatureambient air as well as due to a clogged air filter.

Referring to FIG. 13, combination oven 30 of the present invention alsocomprises an interlock switch assembly 200 that is disposed on a hinge190 that is fastened to door 42 by fasteners 191 and 193 and to a frame192 by a fastener 194. Frame 192 is supported by bottom wall 40. Hinge190 comprises a pivot 195, which is coupled by a spring 196 to a cam197.

Referring to FIGS. 14-17, interlock assembly 200 includes an angledbracket 202 that comprises a first portion 204 and end portions 206 and208 that extend at an angle, preferably a right angle, thereto, atspaced apart locations. Preferably, the spaced apart locations are atopposed ends of portion 204. A plunger 210 has a portion 230 thatextends through openings 212 and 214 of portions 206 and 208 of bracket202, respectively. A fastener 216 extends through an opening 218 inportion 230 of plunger 210 just outside portion 208 of bracket 202.Plunger 210 has a right angle portion 220 just outside of portion 206 ofbracket 202 by a distance depicted as d in FIG. 18. The motion ofplunger 210 is limited to the distance d by the locations of fastener216 and right angle portion 220. Plunger portion 230 comprises a necksection 232 that carries a spring 228 between a stop 234 thereof andportion 208 of bracket 202.

Plunger portion 230 also comprises a cam surface 236 and a cam surface238. A micro-switch 240 has a contact element 242 in contact with camsurface 236. A micro-switch 244 has a contact element 246 in contactwith cam surface 238. Cam surfaces 236 and 238 are shaped such thatmicro-switches 240 and 244 are activated in sequence as plunger moves tothe right or the left as viewed in FIG. 15. For example, the ramps tothe left side of cam surfaces 236 and 238 are offset from one another byan amount that yields the time differential in the sequence ofactivation, i.e., the turning on and off of micro-switches 240 and 244.The motion of plunger 210 is controlled by the motion of cam 197 as ovendoor 42 rotates about hinge 190 of combination oven 30.

Referring also to FIG. 13, the position of plunger 210 is as shown inFIGS. 14-17 when door 42 is open. Spring 228 is in its least compressedcondition. As door 42 is closed, cam 197 engages and moves plunger 210up in FIG. 13 (to the right in FIGS. 14-17). As plunger 210 moves to theright (FIG. 15), contact elements 242 and 246 encounter the left handramps of cam surfaces 236 and 238 in sequence to activate theirrespective micro-switches 240 and 244. For the purpose of description,it is assumed that the left hand ramp of cam surface 236 is encounteredfirst (its ramp is offset slightly to the right from that of cam surface238). Thus, as door 42 is closed, micro-switch 240 is activated firstand then micro-switch 244 is activated. As plunger 210 moves to theright, spring 228 compresses.

When door 42 is opened, spring 228 decompresses and returns plunger 210to the position shown in FIGS. 14-17. As plunger 210 moves to the left,micro-switch 244 is activated first and then micro-switch 240 isactivated. Micro-switches 240 and 244 are connectable in circuit withother components to shut off microwave power, oven heating and reducesfan speed to 10% airflow as door 42 opens. The assembly is robust enoughto assure the correct sequencing of micro-switches 240 and 244 even uponthe occurrence of jarring events, such as slamming of the oven door.

A substantially identical interlock assembly is incorporated in thehinge assembly for the other side of door 42. In addition, the switchassembly application (two interlock assemblies, one on each door hinge)serve to comply with the UL923 safety standard requiring a crowbarcircuit to render the unit safe if a switch were to fail.

A control system (not shown) generates continuous reduced microwavepower without generating large current flicker in the mains powersupply. This is only applicable in a microwave oven containing Nmagnetrons (N>1) where the filament current is supplied separate fromthe high voltage transformers. There are two advantages with thisarrangement. First, the food quality of items rises during cooking.

Due to high complexity of cooking parameters for the variable speedimpingement microwave mode, the controller includes a special controlmode that aids in the recipe cooking parameters. The controller asks forcertain parameters and then suggests suitable cooking parameters. Whenthe cooking is finished, the controller poses questions to evaluate thedesired quality and modifies the cooking parameters automatically with apossible manual override. This will continue until a satisfactory resulthas been achieved and the program can be stored automatically in thecontroller. As described below with reference to FIG. 22, the controllercomprises a CPU (central processing unit), a switching unit withvariable speed drive for fans, a key reader, an input switch matrix, analarm/beeper, a non-volatile memory, a cavity temperature sensor,magnetron temperature sensors and a display module. The controllerincludes the features of uploading and downloading cooking programs(500×8 stages). The controller also includes a cool down mode thatallows a 24/7 store operator to rapidly cool down the oven using ice.This process is fully automated and only advises the operator when theoven is cool and safe to clean. The controller also has a configurationor profile mode that allows individual customers to set up theirpreferred mode of operation, i.e., manual or programmed or preprogrammedonly. Other variables that can be either set by the menu key or by theoperator are beeper loudness, language, oven operating temperature band(to insure consistent cooking results), Degrees F. or C. and whetherduring operation the actual oven temperature or the set temperature isdisplayed. To eliminate prevention of the oven operating due to a dropin cavity temperature when the door is opened the controller utilizes anaveraging mode where a temperature measurement is taken every 30 secondsand the actual oven temperature is calculated from the average of thelast ten readings. Also to help in this area the controller switches theheater on for a fixed period whenever the door is opened.

Referring to FIGS. 18-21, another embodiment of the oven of the presentinvention is shown as oven 250. Oven 250 comprises a pair of outer sidewalls 252 and 254, an outer back wall 256, an outer top wall 258, anouter bottom wall 260 and a front wall 261, all of which comprise anouter enclosure. Front wall 261 comprises a door 262 and a control panel264 above door 262. A handle 268 is disposed on door 262 for opening thedoor in a pull down manner.

Combination oven 250 is configurable for operation in a convection modeand a combination impingement and convection mode.

Referring to FIGS. 20 and 21, oven 250 comprises an oven chamber 270 anda fan box 272 supported by a support structure 266. Oven chamber 270 andfan box 272 share an inner top wall 276, an inner bottom wall 278 andinner side walls 280 and 282. Oven chamber 270 and fan box 272 alsoshare a vertically disposed baffle plate 274. Thus, oven chamber 270comprises door 262, baffle plate 274, inner top wall 276, inner bottomwall 278 and inner side walls 280 and 282. Fan box 272 comprises baffleplate 274, inner top wall 276, inner bottom wall 278, inner side walls280 and 282 and an inner back wall 284. Support structure 266 ismechanically connected to outer bottom wall 260, outer side walls 252and 254 and inner bottom wall 278.

A fan 286 is disposed in fan box 272 and a heater 288 is disposeddownstream of fan 286. Fan 286 may be any fan suitable for circulatingheated air in an oven. Heater 288 may be any heater (gas or electric)suitable for heating circulating air in a convection and/or impingementair oven. Preferably, heater 288 is an electrical heater having one ormore heating elements disposed above and below the blades of fan 286.

Referring to FIGS. 19 and 20, baffle plate 274 comprises a plurality ofopenings to provide a path for air to circulate between oven chamber 270and fan box 272. In particular, baffle plate 274 is mounted offset by anopening or gap 290 from inner side walls 280 and 282 and inner top wall276. Baffle plate 274 is also offset from inner bottom wall 278 by a gap291. Baffle plate 274 also includes an intake port 292 located centrallyand in registration with at least a portion of the blades of fan 286.Intake port 292 comprises a plurality of apertures 294. Fan 286circulates air heated by heater 288 through gap 290 into oven chamber270 and takes in the circulating air via intake port 292 as shown byarrow 296 in FIG. 21.

Although not shown in FIGS. 19-21, a grease filter and/or a catalyst maybe located upstream to the suction side of fan 286 (e.g., at intake port292) to filter grease particles and other contaminates from thecirculating air stream.

Referring to FIGS. 19-21, an oven rack 298 is disposed in oven chamber270 on supports 300 mounted to inner side walls 280 and 282 so that ovenrack 108 is near the bottom of intake port 292. Oven rack 298 may be astandard food rack, i.e., available off-shelf.

Outer walls 32, 34, 36, 38 and 40, which comprise an outer enclosure,inner walls 76, 78, 80, 82 and 84, which comprise an inner enclosure,and baffle plate 74 are preferably a metal, such as stainless steel.

A fan motor 302 is disposed in the space between inner back wall andouter back wall is coupled to rotate fan 286. A suitable thermalinsulation (not shown) is disposed in passageway 120 about oven chamber70 and fan box 72.

Inner walls 276, 278, 280, 282 and 284 are separated from outer walls252, 254, 256, 258 and 260 by a passageway 304 for cooling air in oven250. A cooling fan 306 is disposed in passageway 304 below oven chamber270 and between outer bottom wall 260 and inner bottom wall 278. A fanmotor 302 and other components are disposed in passageway 304. A fanmotor (not shown) is disposed in fan motor compartment 124 and iscoupled to rotate fan 286. A suitable thermal insulation (not shown) isdisposed in passageway 304 about oven chamber 270 and fan box 272.

Cooling fan 306 is operable to circulate cooling air in passageway 304.The cooling air is drawn into passageway 304 from ambient via suitablylocated air intake ports (not shown) and flows through passageway 304and exits via suitably located exit ports (not shown) to cool variouscontrol parts, fan motor 302 and other control parts. For example, theintake ports could be located along outer side walls near outer bottomwall and the output ports in outer back wall 256 as in oven 30 of FIG.1.

For convection operation of oven 250, fan 286 circulates air drawn fromoven chamber 270 into fan box 272 via intake port 292. The air is heatedby heater 288 and circulated to oven chamber 270 via gaps 290 and 291

Referring to FIGS. 19-21, oven 250 is also configurable in animpingement mode by installing a removable lower impingement plate,which is substantially identical to and bears the same reference numeralas lower impingement plate 150 of oven 30. Lower impingement plate 150is dimensioned for installation by sliding motion along inner bottomwall 278. Handle 158 facilitates installation and removal. A pair ofstops 310 (FIGS. 19 and 20) is disposed on inner bottom wall 278 at alocation to engage the sides of impingement plate 150 when it reachesthe fully installed position. Also, a flange 312 is located along thebottom edge of baffle plate 274 to facilitate a flush installation ofimpingement plate 150 and baffle plate 274 to minimize air leakage. Inan alternate embodiment, stops 310 can be replaced with any suitableguide or stop. For example, flange 312 can be suitably shaped to engagethe top of lower impingement plate 150 at one or more locations toprovide a flush fit.

When installed, impingement plate 150 forms with inner bottom wall 278an impingement plenum that is in fluid communication with fan box 272via gap 291 below baffle plate 274. Thus, airflow from fan box 272through gap 291 pressurizes lower impingement plate 150 to provide jetsor columns impingement of impingement air toward the underside of a foodproduct located on oven rack 298, as indicated by the vertical upwardlyextending arrows in FIGS. 20 and 21.

The back side of lower impingement plate 150 has an opening (not shown)to accept air from the gap between the fan cover and the bottom wall ofthe oven. For example, the opening can encompass all (back side totallyopen) or a portion of the back side of impingement plate 150. In theillustrated embodiment the box is shaped so as to slide beneath thebottom edge of baffle plate 274 during installation and removal. Flange312 assists in the sliding motion. Flange 312 and lower impingementplate 150 are dimensioned for the sliding motion and for a relativetight fit to effectively deliver the airflow to the impingement platewith an adequate air pressure to produce the impingement columns withminimal air leakage at the back of lower impingement plate 150.

Referring to FIGS. 20 and 21, a pair of vertical baffle structures 314and 316 is mounted on opposite sides of fan 286 in fan box 272. Wheninstalled, baffle plate 274 is mounted to vertical baffle structures 314and 316. Vertical baffle structures 314 and 316 also serve as baffles orguides to direct more of the airflow around the top and bottom edges anda lesser airflow about the sides of baffle plate 174. To this end, thevertical structures are spaced a slight distance 318 from inner backwall 284 to provide a pair of vertical slots 318, which are narrowcompared to the distance (gap 290) between the top of baffle plate 274and inner top wall 276 and to the distance (gap 291) between the bottomof baffle plate 274 and inner bottom wall 278. Vertical bafflestructures 314 and 316 do not extend above the top of baffle plate 274so as to permit the top airflow to extend from inner side wall 280 toinner side wall 282 of oven 250. On the other hand, vertical bafflestructures 314 and 316 extend below baffle plate 274 to inner bottomwall 278, i.e., the bottom of impingement plate 150. This assures aneven higher airflow into impingement plate 150 and limited side airflowat the bottom to narrow vertical slots 318, thereby assuring a maximalairflow to impingement plate 150. That is, vertical baffle structures314 and 316 baffle the airflow through the narrow slots 318 to be alesser airflow than the flow through gaps 290 above and 291 below baffleplate 274. This serves to maximize the air volume and pressure in lowerimpingement plate 150 to deliver jets of impingement air.

Referring to FIGS. 5 and 19, the less closely spaced jet holes near theedges of impingement plate 150 provides lesser impingement air to thesides of a food product on the oven rack. However, in oven 250convection air also flows around the edges of baffle plate 274 and offinner side walls 280 and 282 of oven chamber 270. This helps withbrowning of the bottom of the food product portions that are near innerside walls 280 and 282.

Oven 250 can alternatively be provided with a removable upperimpingement plate (not shown) similar to upper impingement plate 152 ofoven 30 to provide impingement air from above either in place of or inaddition to lower impingement plate 150.

A microwave facility (not shown) may be disposed adjacent one of theoven walls, e.g., the top wall, and can also be used in a microwave modeor in combination with the heated air stream in either an impingementmode or a non-impingement mode.

Referring to FIG. 22, a controller 400 is shown for oven 30. Controller400 is similar to the controller shown in U.S. Pat. Nos. 6,660,982 and6,903,318, which are hereby incorporated by reference. In particular,controller 400 includes a central processing unit (CPU) 408 that isinterconnected with a key reader 402, a manual control panel 404, adisplay unit 407, an audio alarm/beeper 410, a control interface 409, amemory 411 and oven 30. CPU 408 comprises a processor 405 and a memory406.

Oven 30 comprises an oven temperature sensor 401 that is located in ovenchamber 70. Oven temperature sensor 401 provides a signal that isproportional to the temperature of oven chamber 70. This signal iscoupled to CPU 408.

Key reader 402 is operable to read information carried on a key. Thisinformation may include program data corresponding to different cookingsequences at a data site, and is then sent to the cooking site for usewith oven 30 and optionally with other ovens.

Control interface 409 is interconnected with a number of devices of oven30. To this end, control interface 409 is interconnected with coolingfan 122, oven fan 85, heaters 87, magnetrons 126, a magnetrontemperature sensor 415, an ambient temperature sensor 403 and a memory411.

A plurality of control programs is stored in memory 411 and/or key 400.

Referring to FIG. 23, a cool down program or mode 420 is used by CPU tocontrol a cool down of oven 30. Cool down program begins at start box422 and proceeds to step 424, which tests or samples a currenttemperature of oven chamber 70 provided by oven temperature sensor 401.Step 426 determines if the cavity (oven chamber 70) is too hot. Forexample, step 426 determines if the current oven temperature greaterthan a predetermined temperature limit. If not, the user is informed ondisplay unit 407 that the oven chamber is cool. If step 426 determinesthat the current oven temperature is too hot, the user is instructed toplace a load of ice in oven chamber 70. Step 428 then automaticallyadjusts the speed of fan 85 and/or cooling fan 122. Step 428 then teststhe temperature of oven chamber 70 based on the temperature signalprovided by oven temperature sensor 401. Step 430 determines if thecavity is hot. For example, step 430 determines if the oven chambertemperature above a safe limit at or below which it is safe for anoperator to clean or service oven 30. If yes, cool down mode reiteratesin the loop of steps 428 and 430 until step 430 determines that the ovenchamber temperature has dropped to or below the safe limit. When thishappens, step 432 informs the user that the oven is cool with a messageon display unit 407. Cool down program 400 ends at step 458.

Referring to FIG. 24, a duty cycle control mode 440 is used by CPU tocontrol the duty cycle of the magnetrons. Duty cycle program 440 beginsat start box 442 and proceeds to step 444, which converts totalmicrowave cook time to seconds. Step 446 then divides the total time by40 and calculates a remainder. As an example, assume a total microwavecook time of 50 seconds and a duty cycle of 25%. Step 446 calculates oneinterval of 40 seconds and a remainder of 10 seconds. Step 448 convertsthe remainder of ten seconds into tenths of a second by multiplying by10 for a total of 100 tenths of a second. Step 450 then calculates theon time of magnetrons 126 for the 25% duty cycle of the 40 secondinterval and the ten second remainder. The result is for the 40 secondinterval: 10 seconds on and 30 seconds off and for the remainder; 2.5seconds (250 tenths of a second) on and 7.5 seconds (750 tenths of asecond) off. Step 452 executes the cooking stages at 40 secondintervals, which for the assumed example is one 40 second interval. Step456 then executes a last stage using the remainder on time formagnetrons 126. Duty cycle control mode 440 ends at step 458.

Referring to FIG. 25, a magnetron error program 470 is used by CPU 408to handle magnetron errors. Magnetron error program 470 begins at startbox 472 and proceeds to step 474, which tests the temperature ofmagnetrons 126. Step 474 samples the temperature signal provided bymagnetron sensor 415 to provide a current magnetron temperature. Step476 then determines if the magnetron current temperature is okay. Forexample, the current temperature is okay if it is in a range having apredetermined upper limit of too hot (magnetron overheated) and a lowerlimit of too cold (magnetron shutdown or other failure). Step 480 thenresets a counter. Step 482 determines if the counter value is an error.Since step 480 reset the counter there is no error and magnetron errorprogram 470 would then end at step 486. If step 476 determines that thecurrent magnetron temperature is outside the range, step 478 decrementsthe counter. Step 482 would then determine that the counter value is anerror and step 484 displays a message on display unit 407 informing theuser to disable the oven.

Referring to FIG. 26, a cooling fan control program 490 begins at start492 and proceeds to step 494, which reads the current ambienttemperature from ambient temperature sensor 415. Based on the currentambient temperature, controller 400 adjusts the speed of cooling fan122. For example, the cooling fan speed is adjusted higher for warmerambient temperatures and lower for cooler ambient temperatures.

Referring to FIG. 27, a profile program 500 begins at start 502 andproceeds to step 504, which reads a default oven profile. Step 506displays the default oven profile on display unit 407. For example, theoven profile includes a plurality of parameters affecting the userinterface, such as language to be used, temperature units ° F. or ° C.,manual or program mode, beeper volume or sound and others. The user atstep 510 can input changes to the profile parameters. Step 512 validatesthe entered changes. Step 508 determines if the user has entered anychange. If yes, step 514 modifies the profile and step 506 displays thechange. The user can then edit the change or make other changes. Ifother changes are made, profile program 500 iterates in the loop ofsteps 506, 508 and 514 until step 508 determines that the user has notentered a change. Step 516 then determines if the profile entry is thelast profile parameter. If not, profile program 500 returns to iteratein the loop of steps 506, 508, 514 and 516 until step 516 determinesthat the current profile entry is the last profile entry. Step 506displays the next profile parameter and steps 508 and 514. Profileprogram then ends at step 518.

Referring to FIG. 28, a down and upload program 530 controls data andprogram downloads and uploads between controller 400 and menu key 400.Download and upload program 530 begins at start 532 and proceeds to step534, which detects a menu key 400 at key reader 402. Step 536 identifieswhether menu key 400 is inserted for a firmware upload, a programdownload or a program upload.

If step 536 identifies a firmware upgrade, down and upload program 530enters a firmware upload routine 540. Firmware upgrade routine 540begins at step 541, which identifies the firmware. Step 542 transfersthe firmware to CPU memory 406. Step 543 performs a checksum of thefirmware data. Step 546 determines if the firmware update is okay. Ifyes, step 547 displays a message on display unit 407 that the upgrade isokay. If no, step 547 displays a message on display unit 407 that theupgrade is not okay. Firmware upgrade routine 540 then ends at step 548.

If step 536 identifies a program download, down and upload program 530enters a program download routine 550. Program download routine 550begins at step 551, which identifies the programs to be downloaded. Step552 transfers the programs to memory 411. Step 553 performs a checksumof the program data. Step 554 determines if the program download isokay. If yes, step 556 displays a message on display unit 407 that theprogram download is okay. If no, step 556 displays a message on displayunit 407 that the program download is not okay. Program download routine550 then ends at step 557.

If step 536 identifies a program upload, down and upload program 530enters a program upload routine 560. Program upload routine 560 beginsat step 561, which identifies the programs to be downloaded. Step 562transfers the programs to memory 411. Step 563 performs a checksum ofthe program data. Step 564 determines if the program upload is okay. Ifyes, step 565 displays a message on display unit 407 that the programupload is okay. If no, step 565 displays a message on display unit 407that the program upload is not okay. Program upload routine 550 thenends at step 566.

The present invention having been thus described with particularreference to the preferred forms thereof, it will be obvious thatvarious changes and modifications may be made therein without departingfrom the spirit and scope of the present invention as defined in theappended claims.

1. An oven comprising: a frame, a door and a hinge that is connectedwith said door and said frame for rotating said door about a pivot assaid door is opened and closed; a cam that moves as said door rotates;an interlock assembly that comprises first and second switches and thatresponds to the motion of said cam to activate said first and secondswitches in sequence as said door opens and closes.
 2. The oven of claim1, wherein said first and second switches are micro-switches.
 3. Theoven of claim 2, wherein said interlock assembly further comprises aplunger that is mounted for reciprocal motion and that activates saidfirst and second micro-switches in response to said cam motion.
 4. Theoven of claim 3, wherein said plunger is shaped to control saidsequence.
 5. The oven of claim 4, wherein said first and secondmicro-switches comprise a first contact element and a second contactelement, respectively, that are engaged by and tripped by the reciprocalmotion of said plunger.
 6. The oven of claim 5, wherein said plunger isshaped with first and second contours that are disposed in engagementwith the first and second contact elements of the first and secondmicro-switches, respectively, wherein said first and second contours areshaped to activate the first and second micro-switches in sequence assaid plunger is moved.
 7. The oven of claim 6, wherein said interlockassembly further comprises a spring that compresses as said door closesand decompresses as said door opens to return said plunger to a dooropen position.